As semiconductor device feature sizes continue to shrink, the charge carrier depletion of gate electrodes made of polysilicon becomes a serious issue. One approach to resolving this issue is to replace polysilicon gate electrodes with a metalized (e.g., metal silicide) gate electrode. Integrating metal silicide gate electrodes into semiconductor device fabrication can be problematic, however. For instance, the steps to form a metal silicide gate electrode can inadvertently cause excessive silicidation of metal silicide source and drain contacts. Consequently, the metallization of source and drain contacts and, the metallization of the gate electrode, are often done at separate stages in the device fabrication process. Typically, the gate electrode is metalized first, and the source and drain regions are metalized later in the process. The already-metal silicided gate electrode can be damaged, however, when performing certain conventional processes to form the metal silicide source and drain contacts.
Accordingly, what is needed is a method for manufacturing semiconductor devices having metal silicide gate and source drain electrodes that addresses the drawbacks of the prior art methods and devices.